The present invention relates to an instrument panel of a motor vehicle or similar molding of foam resin having a layer of foam resin and, more particularly, to a molding of foam resin which carries an air duct or similar hollow member integrally therewith.
In general, an instrument panel of a motor vehicle has a laminate structure which is made up of a substrate, a covering, and a padding layer intervening between the substrate and the covering and made of foam polyurethane or similar foam resin. While the substrate has traditionally been implemented by hard resin such as ABS resin, a current trend in the art is toward a substrate which is also made of foam resin for the ease of fabrication. In this kind of instrument panel, the substrate and padding layer are formed together as a single molding of foam resin.
A hollow member such as an air duct which forms a part of an air conditioning conduitwork has to be mounted on an instrument panel and has to be surely fixed in place thereon. With an instrument panel having a substrate made of foam resin as stated above, it is extremely difficult to securely mount an air duct or similar part on the outer periphery of the panel. It has been customary, therefore, to bury such a part in the foam resin layer.
FIG. 3 indicates a prior art configuration of a molding of foam resin in which a hollow member is buried, together with a procedure for fabricating the molding. As shown, the molding is composed of a covering 1, a substrate 2 made of foam resin and provided on the back of the covering 1, and a hollow member 3 fully embedded in the substrate or foam resin layer 2. To fabricate this kind of molding, the covering 1 is laid on the working surface of a lower mold 4, then the hollow member 3 is placed on the upper surface of the covering 1 with the intermediary of a suitable support member 5, and then an upper mold 6 is closed. Subsequently, an undiluted solution of foam resin is introduced in the space defined between the covering 1 and the upper mold 6 and is caused to foam and solidify. The hollow member 3 is surely fixed in place in the molding because it is fully embedded in the foam resin layer 2 and because it is bonded to the foam resin layer 2 by the foam resin which contacts the surfaces of the part 3 before solidification. Since the molding is fabricated with the hollow member 3 being buried therein, an extra step of mounting the part 3 after the fabrication is not necessary.
However, a problem with the molding of the type shown in FIG. 3 is that the foaming pressure of the foam resin directly acts on the hollow member 3 during the course of formation of the foam resin layer 2, tending to deform the hollow member 3 such as an air duct. The deformation of the hollow member 3 due to the foaming pressure may be eliminated by filling the member 3 with air, water or similar fluid, then molding the foam resin layer 2, and then discharging the fluid from the part 3. This, however, cannot be practiced unless the fluid is introduced in and then discharged from the hollow member 3 by extra steps, resulting in an increase in the number of fabricating steps.